Rotary drill bits used in earth drilling are generally comprised of a cast, forged or machined material of significant hardness, to keep wear to the drill bit head to a minimum. To further enhance the effect of the drill, drill bit heads often utilize a plurality of hardened studs of tungsten carbide or other hard material mounted in a configuration on the head of the drill bit to increase the durability and efficiency of the bit. Conventionally, these studs are mounted in their seats upon the head of the drill bit by brazing or cementing them to the drill bit, which is economically inefficient, time consuming, and often results in the loss of studs during vigorous drilling. Furthermore, it is often necessary for the bits to be heavily machined after casting or forging prior to the attachment thereto of any carbide studs, requiring additional labor and costs.
U.S. Pat. No. 4,607,712 to inventor Larsson teaches a rock drill bit with studded inserts positioned within drilled holes, following the casting of the drill bit. This additional step of requiring the bit to be machined prior to the attachment of the studs requires significant amounts of resources and time.
U.S. Pat. No. 4,181,187 to inventor Lumen, teaches a method of attaching inserts to a rock drill bit using a press to force the hardened metal inserts into pre-bored holes in the rock drill bit head. Exemplifying the obstacle of extra tooling of the drill bit head following the casting, the present invention overcomes this by providing a cast drill bit head with hardened stud inserts already attached to the drill bit head during the casting process.
U.S. Pat. No. 4,499,795 to inventor Radtke teaches another method of drill bit manufacture wherein soft iron or steel plugs are embodied in the mold. After casting, the plugs are subsequently drilled out and cutting studs are inserted in their place. This extra machining significantly increases production time and cost to the drill bit. That will allow the final side to come
U.S. Pat. No. 4,014,395 to inventor Pearson discloses a rock drill bit assembly wherein the hardened drill inserts are maintained in pre-drilled apertures in the head of the drill bit by tapered sleeves that are pressed into place around the studs. The addition of the sleeves increases production costs as well as the possibility of the incidental release of the studded insert due to the vibrations caused by the earth drilling process.
The present invention overcomes these problems, by providing a method of manufacturing a downhole drill bit with pre-cast carbide studs, creating a time and cost efficient alternative to the traditional methods of manufacturing requiring post-casting attachment of the carbide studs, followed by subsequent machining prior to use of the drill bit.